The widespread use of internet-based technologies has made available more content to more users than ever before. Moreover, the capability of individual users to provide content which is then accessible via the internet to many other users is also a further effect of the widespread use of the internet. Such user provided content need not only be by way of a user providing and maintaining her own web page or the like, but may also be provided by users providing content to existing websites, newsgroups, bulletin boards or the like, which content may then be accessed by other users. Such content provision systems are a form of peer to peer (P2P) system.
It is possible to identify three general classes of P2P systems:
i) where service is provided by individual peers, and is generally consumed by other peers such that service provision and remuneration is inherently pairwise. Prior art examples of such peer to peer services are Gnutella (see www.gnutella.com) and Kazaa (see www.kazaa.com).ii) where service is provided by a group of peers (eg fragmented file downloads, such as http://bitconjurer.org/bitTorrent); andiii) another in which service is effectively provided by the entire group of peers (‘emergent service provision’, ESP), and is, potentially, effectively consumed by all peers. Examples of such systems are newsgroups, review websites, bulletin boards or the like.
Within the first and second classes of P2P network mentioned above the problem has been identified that some peers provide a great many of the content items available for download, whilst the majority of users share little or no files. Vishnumurthy et al in Karma: A Secure Economic Framework for Peer-to Peer Resource Sharing Procs Workshop on the Economics of Peer-to-Peer Systems, Berkeley, Calif., June 2003 report that 20 to 40% of Napster and almost 70% of Gnutella peers share little or no files, and comment that this is unsurprising as there is little incentive for peers to contribute resources. Vishnumurthey et al further describe a proposed framework to address this problem, where each peer has single scalar value referred to as Karma, which is increased as resources are contributed, and decreased when resources are consumed. In order to be able to download a file, therefore, the peer must have sufficient Karma in its “account” to be able to afford the download.
A similar system addressing the same problem is described by Gupta et al in A Frequent-Sharer Program for Peer-to-Peer Systems, downloadable from http://www.cc.gatech.edu/grads/g/Minaxi.Gupta/pubs/tr-incentives.pdf. Here, peers earn points as they serve content, and a peer is subsequently provided a level of service (LoS) based on the number of points she earns in the system. In order to ensure that peers continue to serve content even after earning points and becoming eligible for an enhanced level of service, points earned by a peer expire periodically. Hence, peers have to keep contributing to the system in order to retain or upgrade their LoS.
However, the same problem of encouraging contributions also exists in the ESP P2P system, such as a newsgroup. Generally newsgroups function by members posting newsworthy information, or by asking a question and having others respond to that question. The economic structure is therefore that peers make contributions to the community, and all members of the community then receive benefit. A strong characteristic is that the inherent cost of contributing is very high, whilst the cost of consumption is minimal. Even the cost of repeated acts of consumption is minimal.
Typically, the real utility of such an application (to end users) generally comes from the combination of the initial question, and public answers to that question—ie it is an emergent property, with service effectively provided by the entire group of peers. Many members of the community (potentially, at least) receive benefit from the discussion. As mentioned previously, there are many similar situations with this characteristic, especially those in which the contribution is human-generated content (which inherently has very high costs), such as websites which provide user reviews.
The present invention aims to address the above described problem of incentivising contributions particularly, although not exclusively, in peer to peer systems with emergent service provision attributes.